StringModel looks ambigious to me, will it extend
- LoadableDetachableModel
- IModel
- Model
- AbstractReadOnlyModel
- ....
???
Am 14.05.2008 um 15:47 schrieb Doug Donohoe:
Let me outline what I believe the benefits are. For example:
add(new Label<String>("tournamentName", tournament.getName()));
add(new Label<String>("hostName", game.getHostPlayer()));
row.add(new AttributeModifier("class", true, new
Model<String>(row.getIndex() % 2 == 0 ? "odd" : "even")));
add(new StringLabel("tournamentName", tournament.getName()));
add(new StringLabel("hostName", game.getHostPlayer()));
row.add(new AttributeModifier("class", true, new
StringModel(row.getIndex()
% 2 == 0 ? "odd" : "even")));
Sure, it seems like a small difference and a saving of two
characters, but
here is what I believe are the benefits of doing this:
1) I can more easily use the features of my IDE such as auto-
completion
2) Find Usages is more accurate (at least in IntelliJ, where I'm not
aware
of a find-usages that scopes to a particular generic type)
3) Let's face it, Generics clutters up your code and makes it harder
to
read. This simplifies things a bit.
In answer to Martijn's assumption (in a separate post) that I was
going to
iterate over all java types and all wicket types: that is an
incorrect
assumption. Obviously, I would want to pick the most common use
cases and
seek feedback from the community. Let us not dismiss it outright. I
believe this is a valid topic of conversation. Generics are new to
Wicket
and still unused by many Java APIs and likely new to many
programmers. I
can tell you that using classes such as this made it much quicker
and easier
to remove all the warnings that showed up in my code when I migrated
to 1.4.
It seems easier to replace common usage from before (new Label(...))
with
new StringLabel(...) rather than new Label<String> (even typing
that now
was more difficult). In any case, there may be some complaining
about the
extensive use of Generics in 1.4 once it is released. This may make
it
easier to transition. Maybe not. At least let's be open to
discussing it.
Finally, in answer to the point about "negating the point of
generics", I
respectfully disagree. One major point of generics is to avoid code
duplication of boilerplate code. It it weren't for the need to
create
constructors, there wouldn't be any duplicated code. I agree that
it is a
fine balance to strike, but there are competing needs of readability
and
maintainability.
-Doug
Hoover, William wrote:
imho, that seems like that adds a lot of unnecessary code. One of the
nice things about Wicket is that it keeps the bloat to a minimum.
-----Original Message-----
From: Doug Donohoe [mailto:[EMAIL PROTECTED]
Sent: Wednesday, May 14, 2008 8:21 AM
To: users@wicket.apache.org
Subject: Re: Using generics with some non-generic classes in Wicket
Somewhat related to this thread, when I moved to generics win Wicket
1.4, I created some utility classes such as:
public class VoidContainer extends WebMarkupContainer<Void> public
class VoidPanel extends Panel<Void> public class StringLabel
extends
Label<String>
public class IntegerModel extends Model<Integer> public class
StringModel extends Model<String> public class DateModel extends
Model<Date> public class DoubleModel extends Model<Double>
And so on. This made my wicket code cleaner and easier to use. I
think
the Wicket 1.4 generics implementation is headed in the right
direction.
It was a pain at first because I had to parameterize everything, but
creating convenience classes like this made it easier.
I'm thinking about creating a patch with a suite of these types of
classes because I think users will want something like this.
-Doug
Johan Compagner wrote:
The problem is that wicket needs an annotation
<genericsOptional>
so that all the warnings about raw types are gone.
A component only has to be generic if you use the IModel constructor
or call getModel(), getModelObject() methods..
for the rest it is not really needed
johan
On Wed, May 14, 2008 at 9:28 AM, Sebastiaan van Erk
<[EMAIL PROTECTED]>
wrote:
My post kind of missed the point, I shouldn't post when I'm already
half asleep. :-)
Obviously MarkupContainer satisfies the MarkupContainer<?> in a
method argument, so it accepts the raw type. However, it
generates a
warning because the method says it's generified, so you should be
using the generic type.
Johan Compagner wrote:
I dont care, because i cant do any thing with the ? The only thing
it enforces is that it must now be a generic class which is
annoying. Not to mention that in that area eclipse and javac
accept
different things....
The reason it warns you to use generics when generics are wanted is
because Sun wants to be able to make it *required* (in a future
release) to use generics where generics are wanted; at least, so I
read... I think in the real world they wouldn't dare to do this
because it would piss off so many users and break so much
stuff. :-)
But the idea is that if something is generified you should be
using a
type parameter, and using a raw type is *purely* for backwards
compatibility with legacy code.
Regards,
Sebastiaan
So or we in wicket dont use <?> any where and have supress warning
everywhere for that or we do use it and then suddenly it is in my
eyes restricted to much.
I don't understand
On 5/14/08, Sebastiaan van Erk <[EMAIL PROTECTED]> wrote:
Johan Compagner wrote:
yes thats the reason
you are calling the method add with a generified component but
that container itself is not generified
i dont like this about generics expecially the onces like this:
add(MarkupContainer<?> container)
then suddenly a none generified component cant be added...
thats really stupid <?> should mean anything.. including none
generics
No, that's not correct. For example, List<?> is much more
restrictive than a raw List (which is a List). To a raw list you
can add an instance of any type whatever, i.e., list.add(new
Object()). But in List<?> the ? is a wildcard which says it could
be any type there, i.e., it could be a List<Integer>. But you
can't add a new Object() to a List<Integer>!
Thus MarkupContainer<?> means "MarkupContainer parameterized by
some unknown type", and *not* MarkupContainer parameterized by
Object, which is what the raw type means.
Regards,
Sebastiaan
johan
On Tue, May 13, 2008 at 5:55 PM, Stefan Simik <
[EMAIL PROTECTED]>
wrote:
I have one idea,
the reason of the warnigs is, that parent of
AjaxPagingNavigator is PagingNavigator, which has parent
Panel ---> that is not parameterized.
The same problem is with LoopItem, which extends the
WebMarkupContainer ---> that is not parameterized.
? could this be the reason ?
Stefan Simik wrote:
Mhmm, it is meaningful ;) I will know in future, thx
One of the last occuring warning is, when working with
MarkupContainer#add(...) or #addOrReplace(...) method.
Example: I have a simple AjaxPagingNavigator, to which I
add a simple ListView
---------------------------------------------------------------------
--
ListView<Integer> menu = new ListView<Integer>("id",
numbers){
//....populate metods
}
add(menu); //warning here
The warning says:
"Type safety: The method add(Component...) belongs to the
raw type MarkupContainer.
References to generic type MarkupContainer<T> should be
parameterized"
I cannot find out, what's the warning reason, because
ListView self is parameterized.
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